Different render time for the same project -AE 21 18.1

Hi guys,

I 've got some question...

I made test with my project, i observe the time of my render change with this two situation :

•  When i restart my computer, my render time was 27m43s
• Without restart my computer, my render was 1m53s

My project was :

Duration: 29s

3D project (no C4D 3D)

Render with CUDA

Computer spec :

Have you got some explication why my render change like this.

PS: it's my first topic, i'm sry if i forgot something.